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Author Topic: concrete vs resilient mounting  (Read 44268 times)

mobile_bob

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concrete vs resilient mounting
« on: October 04, 2006, 03:59:04 AM »
I would like to submit the following for everyone's consideration, this post is not to suggest any
way over another of mounting an engine.  It is basically the most coherent analysis of what has been discussed that I  can come up with. I will try to break it down into components, sometimes simplistic and at other times a bit more complex, in the effort to try and pull the discussion together.

There are two opposing sides at play here, (1) the use of concrete as the only way to mount the engine, and, (2) an alternative method using steel and resilient mounts

In the following paper I will attempt to examine critically both positions, first stating the position
and then examining the position and determine support for that position.

A. "Mr. X  supports the contention that lister only specified concrete as the material of choice for mounting the engine, "

   To date I have seen no documentation as to why the concrete block was to be used, only that it must  be  used to support the warranty.  By documentation I mean supporting engineering text that clearly shows the need for the concrete base, not advertising literature but the math and physic's to support its use. Lacking such documentation one cannot assume whether the use of concrete is mandatory or not from an engineering standpoint.

B. "Mr. X further contends that lister made no recommendation as to the use of anything other than concrete, and specifically that they never mentioned the use of resilient mounts."

   Just as in (A) above I have not seen documentation that lister even tried resilient mounts.
   Again without supporting documentation in engineering terms we cannot assume that the       use of resilient mounts are inherently good or bad.

C. "Mr. X further states that the concrete block was an integral part of the design of the engine"

   Here again to date I have seen no documentation that the concrete block was an integral       part of the engine design. Further anything that is bolted rigidly to the crankcase becomes       part of the crankcase for purposes of transmission of vibration, resonance, and vector       analysis.

   Examining the contention that the concrete block was an integral part of the engine design the engineers in their wisdom would have had to work out all the math/physic's of    a number of parameters all based on the specific use of the concrete base.

   The problem with this contention is the same engine crankcase was also used on the SOM wherein a cast iron base (which bolted to the engine block become part of the crankcase) is used as an intermediary component between engine and concrete block. The use of a cast iron sub frame would require differing physic's, vectors etc. to enable the concrete to still become part of the crankcase. This assumes the contention that the block of concrete was an integral part of the design.

It therefore cannot be an integral part of the design of the engine, because both engines whether mounted directly on concrete or mounted to the concrete via the cast iron base are the same engines, using the same castings.

        So can we assume that the use of concrete as a mounting base is or is not the only way to mount it?  No

        Does it allow room to explore other possibilities of mounting? such as resilient mounts? Yes


Now the opposing side


(D) Mr. Y contends that much has changed technologically in the last 50 odd years

   Mr. Y, needs to understand and accept that while technology has advanced the basic       physics have not changed. Materials in some cases have changed, but cast iron is still cast iron today as
it  was 70 years ago. Resilient mounts while made of better material today follow the same physic's they did back then. Very little is truly new, and practically nothing related to these engines is any different today than it was 50 years ago.


(E) Mr. Y contends that the engine can be mounted on a steel frame with resilient mounts

While anything can be mounted to anything else with sufficient effort, Mr. Y should be aware of the problems he will encounter in doing so. Should the engine be bolted to a substantial steel sub frame with quality components and then bolt the sub frame to the concrete base, technically he should have no problems or safety issues. Basically he will have a steel SOM base. Which arguably may be superior in strength to the original SOM cast iron base.

The problem however arises with the use of resilient mounts and the stresses that will be imparted back not only to the steel sub frame but to the engine block itself. Remember the steel sub frame is now part of the crankcase.

Resilient mount positioning will be critical, and should be in line with the plane of the crankshaft, not below the crankcase as is typically described by those wishing to use this method of mounting.

The question then arises on how to raise the centerline of the mounts to the same plain as the crankshaft centerline? This is where one can get into all sorts of trouble, this is where the highest stresses will be transferred. That being the transmission from the lower frame mounts to the risers. Presumably one would have to weld the frame risers unless he can have the side rails of the steel sub frame mandrel bent to raise the mount to the centerline of the crankshaft. These welds will have significant stresses imparted on them, and over    the course of time will likely fatigue and fail if not properly designed and executed.

Also it is well  worth noting that the engine will exhibit what is known as "critical speeds" which in stationary use the engine should not be running in. These critical speeds are evident when spinning up and down of the engine it passes through rpm ranges where the vibration and stresses are dramatically higher than at rated speed. Provisions have to be made to limit this mode of operation and to provide a measure of additional support for the engine while in the "critical" engine speed range. This adds another layer of complexity to the design.





in conclusion:

there is no clear evidence that the use of concrete is an integral part of the engine design, further there is no evidence that supports that it is the only way to mount it.  Clearly the use of concrete has proven to be a time proven design, a safe design that works. It has proven to not have any detrimental effect on the engine and it could be argued that it has improved longevity of the engine, even though no studies have been done.

The use of a steel sub frame that is securely mounted to the concrete block should provide a safe and sufficient mounting for the engine, that is well within most DIY'ers capabilities.  Also the use of relatively thin and dense pads should cause not adverse effects on either the engine or the safe operation of the engine, although not providing much in the way of abating the transmission of vibration.

The design, manufacture and use of a steel sub frame and resilient mounts should be possible provided that the design is well engineered and fabricated following accepted engineering standards.  It is my conclusion that this may be well beyond the capabilities of the average DIY'er.


   My hope in presenting this thread/post/paper is to cut through the feeling, thoughts and conjecture that has been prevalent in the discussion, and to narrow it to the basics at hand.
Again I am not going to suggest one method of mounting and engine over another. Should the end user of an engine not feel he understands fully the forces at play I would strongly suggest the use of either concrete direct mounting or a steel sub frame directly mounted to the concrete.

hopefully this will be accepted by all in the spirit it was written
I invite constructive criticism, thoughts and questions, and of course opposing views  :)

bob g
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Procrustes

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Re: concrete vs resilient mounting
« Reply #1 on: October 04, 2006, 06:18:21 AM »
I don't get it Bob.

Without a doubt the technology has advanced since the age of the Lister.  Kubota and others make excellent diesel engines which use convenient flexible mounts.

The designer of the engine we all revere plainly specified the use a concrete block.  Does it make sense to revere the engine but regard as quaint the designer's installation instructions?

Hotater learned the hard way to use a block, and documented it clearly.

I guess in his passion Guy overstated the risk of out-of-spec mounts.  Still, if you believe this old technology is still vital, why do you believe the mount is old fashioned?

Surely there's a place for alternative mounts, maybe in the majority of situations.  How many of us are off grid? Of those, how many really need tens of thousands of hours out of these engines?  If you want to do it right, though, it's hard to imagine a safer bet than following the manual.

mobile_bob

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Re: concrete vs resilient mounting
« Reply #2 on: October 04, 2006, 06:50:32 AM »
Pro:

what don't you get?

maybe it is just late, and i am too tired, but you seem to be on both sides of the issue, or am i missing something?

i wrote a responce to your reply, but after doing so i scrapped it because you appear to be back and forth a bit..

please clarify, is there a problem with my original post?

specifically?

bob g
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Procrustes

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Re: concrete vs resilient mounting
« Reply #3 on: October 04, 2006, 07:22:06 AM »
what don't you get?

maybe it is just late, and i am too tired, but you seem to be on both sides of the issue, or am i missing something?

You're right, my post was confusing.

What I meant was, I've read lots and lots of discussion about how to mount Listers, but IMO if you want to do it right, RTFM.

If you want to reap the fruits of modern technology, get a Kubota.  They're wonderful, and easy to mount.  If you want to pursue time-tested engineering, then do just that.

RA Lister's glory occurred at a time and place where one might expect to use a stationary engine for decades and to pass it along to kin and to run it for tens of thousands of hours.  That's vanishingly rare in our place and time.  If you won't run an engine for more than a few thousand hours, it likely won't make much difference how you mount it, so sure, take a shortcut -- but don't fool yourself that you're doing it right.

What I don't get is all the discussion about the right way to do it, the right way is plain as day.

I'd been holding off on making that post, but when this new thread opened I went ahead.  I wish I hadn't now that I think it through though; I didn't say anything novel.  Sorry for diverting your thread.

slowspeed1953

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Re: concrete vs resilient mounting
« Reply #4 on: October 04, 2006, 08:19:44 AM »
Well here's what I think. It really doesnt fucking matter how you mount your engine as long as you are happy with the way you mounted your engine. Im sure Hotater has a true sense of pride in a job well done, it was a huge effort and hopefully satasified his fondest mounting desires.

Screw the manual's mounting reccomendation that shit is so damn antiquated at this point in time to me its not even funny. Ill mount my engine on what will stand my willie and statisfy my fondest mounting desires and that will be on a set of modern air filled industral mounts made for machines like hammer mills and other ultra heavy duty equipment. The added peace from a vibration free setup by far out weighs the minute chances of catastrophic simultanious multiple mount failures.

Peace&Love :D, Darren

GuyFawkes

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Re: concrete vs resilient mounting
« Reply #5 on: October 04, 2006, 04:14:31 PM »


A. "Mr. X  supports the contention that lister only specified concrete as the material of choice for mounting the engine, "

   To date I have seen no documentation as to why the concrete block was to be used, only that it must  be  used to support the warranty.  By documentation I mean supporting engineering text that clearly shows the need for the concrete base, not advertising literature but the math and physic's to support its use. Lacking such documentation one cannot assume whether the use of concrete is mandatory or not from an engineering standpoint.

Correct.

However I very much doubt you have seen "maths & physics" like this from any engine manufacturer, I'll lay money on it.

So to put this in perspective there is nothing unusual going on.


Quote

B. "Mr. X further contends that lister made no recommendation as to the use of anything other than concrete, and specifically that they never mentioned the use of resilient mounts."

   Just as in (A) above I have not seen documentation that lister even tried resilient mounts.
   Again without supporting documentation in engineering terms we cannot assume that the       use of resilient mounts are inherently good or bad.

Lister were in the business of selling engines, you can assume that they would do nothing to limit the possible market by arbitrarily omitting to mention certain installation options, particularly as said options were common across other models in the range.
Quote

C. "Mr. X further states that the concrete block was an integral part of the design of the engine"

   Here again to date I have seen no documentation that the concrete block was an integral       part of the engine design. Further anything that is bolted rigidly to the crankcase becomes       part of the crankcase for purposes of transmission of vibration, resonance, and vector       analysis.

   Examining the contention that the concrete block was an integral part of the engine design the engineers in their wisdom would have had to work out all the math/physic's of    a number of parameters all based on the specific use of the concrete base.

   The problem with this contention is the same engine crankcase was also used on the SOM wherein a cast iron base (which bolted to the engine block become part of the crankcase) is used as an intermediary component between engine and concrete block. The use of a cast iron sub frame would require differing physic's, vectors etc. to enable the concrete to still become part of the crankcase. This assumes the contention that the block of concrete was an integral part of the design.

It therefore cannot be an integral part of the design of the engine, because both engines whether mounted directly on concrete or mounted to the concrete via the cast iron base are the same engines, using the same castings.

        So can we assume that the use of concrete as a mounting base is or is not the only way to mount it?  No

        Does it allow room to explore other possibilities of mounting? such as resilient mounts? Yes

You have an extra undocumented assumption or two in there, some of them are patently flawed.

a/ the size of block used for a s-o-m base will be much larger than a block used for a pump base.

b/ listeroids ship the bare motor, lister very very rarely shipped a bare motor unless you were an OEM, just about everything came on some sort of iron or steel base.

c/ the documentation that I provided for download was for a start-o-matic as well as the bare cs 6/1, both specified the concrete block

d/ nobody has looked at a lister base, eg nobody has opened their eyes.

Bob, I as you know don't know dick about you, I don't know if you have a single qualification to your name or not, what I do know is what I have observed, you work your way methodically through problems and you don't skip steps unless you don't see them, and even then you will look backwards now and again in case you missed something.

The lister bases, whether iron or steel, were a honeycomb when viewed from underneath, you are smart enough to work out why.

Nobody has ever asked me if I ever did or saw done any analysis of the loads on a lister, there is a pretty big clue in the four 3/4" bolts lister used, guy incognito is in between branding me a luddite playing with spreadhseets and coming up with forces of 150 kilos on the engine mounts, and slightly worried by it, y'all could have asked me because I have seen these tests done with proper strain gauges and data capture on a 6/1 driving a hydraulic pump under the full range of loads, and guy incognito is nearly an order of magnitude out, I saw amplitude ranges of in excess of 1000 kilos under certain conditions, and some of the second and third order harmonics of these loads were a bitch too..... again, those 3/4" bolts lister used make a lot of sense if you look at them with an open mind and let what you are looking at seep in and percolate.

The concrete block also allowed you to follow lister directions and leave the top few inches of bolt free and unfixed, so those loads are spread along a length of bolt instead of being concentrated in one point, all for fatugue see.

If you have an engine that is dancing, eg an engine that you can stick a feeler gauge under when it is running, then by definition there was enough force reacting on the engine to reduce its effective "weight" to zero momentarily.

Scott doesn't like the vibes, a 70 kilo man stamping his feet in turn can produce 100 kilo impacts each foot with no great effort, and you won't hear that vibration, or feel it, any distance away.

There is this disconnect between what is literally staring people in the face, and what they think they see.

The "errors" introduced ALWAYS scale the problem down, that is human nature. The engineer has to consider these factors.

You will "get" it bob, the penny is dropping already to coin one phrase, and to coin another keep at it and you will hear the sound of the other shoe falling too.
--
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Current status - project / standby, Fuel, good old pump diesel.

mobile_bob

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Re: concrete vs resilient mounting
« Reply #6 on: October 04, 2006, 05:20:38 PM »
boy oh boy,, this cracks me up :)

or rather proves out a contention that Guy has made all along, that being folks will read something and take from it just what they need
to support whichever direction they were going in the first place, however out of context thier take might be.

i gave that post some time and some serious thought, and quite frankly i am quite amazed at some of the responces, but that is ok.
at least it narrows the scope to perhaps some specifics that i am still questioning and might prove educational to some.

Guy:
i accept the use of concrete, because of empirical evidence, not engineering evidence.
if you would further like to discuss and enlighten me in this regard, please do so, really i am very interested.

Darren:
 chill out my friend, the post was never intended to piss anyone off, rather to tighten the discussion
and to perhaps get to a few answers. Surely you are smarter than that.

Pro:
thanks for clarifying your position, i was unsure with your first responce.
i would suggest you go back and reread my conclusion,  yes the concrete block is the default mounting method
and for good reason, that being "empirical". At least for now, or until the discussion proves otherwise.


it is plain as day that this subject has become one of the group

that being subjects you don't discuss in polite company,

"religion, politics, and lister/oid mounting"

bob g




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Procrustes

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Re: concrete vs resilient mounting
« Reply #7 on: October 04, 2006, 06:35:34 PM »
Pro:
thanks for clarifying your position, i was unsure with your first responce.
i would suggest you go back and reread my conclusion,  yes the concrete block is the default mounting method
and for good reason, that being "empirical". At least for now, or until the discussion proves otherwise.

I re-read your conclusion Bob, but for my final remark on the topic I can only repeat that I don't get it.  There is possible utility in a thread along the lines of, how much of a shortcut should I take for X requirements?, but RA Lister's manual incorporates millions of hours of runtime, years of engineering, and untold failure analyses.  How much weight can our armchair discussion have exactly?

mobile_bob

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Re: concrete vs resilient mounting
« Reply #8 on: October 04, 2006, 06:56:12 PM »
Pro:

that is the fundamental difference between you and me i suppose.

you accept as fact because that is what you are told or read, i accept what as fact, only after scrutinizing what i have been told or read. 

we both come to the same conclusion although from different approaches

again i accept the solution, but do not accept as of yet the reasoning as being fact


Basically if the answer is concrete, then i want to see the calculations or the lister work that brought them to their conclusion.

this is no different than Guy asking Guy Incog for his math to support his contention that a particular resilient mount will work.

GI asserts that abc mount will work for the intended purpose, and Guy asks to see his computations.  That is fair is it not?

so conversely

if Guy asserts that xyz mount will work, then i should be well within reason to ask to see the computations, That too is fair is it not?


bob g
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SCOTT

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Re: concrete vs resilient mounting
« Reply #9 on: October 04, 2006, 07:18:21 PM »
Last week I spoke with a mechanical engineer about using resilient mounts for a Lister type engine.  He said it should not be a problem, I sent a sketch of the frame the engine would be mounted to.  This sketch shows cross bracing and additional widening of the footprint that are not part of the base in the video I put on Google.  Once I have something from him I will share it.

One of the members did not give this plan much credence because I am not an engineer and thus am not qualified to know if what the engineer comes back with is worth anything.  I completely disagree but let’s just assume that is the case for now.

I decided to get the answer from the most qualified to discuss this topic, the Lister Petter company.    I called Lister Petter today and spoke to a member of the engineering department.  I explained that I wanted to mount a 6/1 engine to a rigid steel frame and mount the frame using resilient mounts to the slab of a garage. (I used a 6/1 as an example because it was easier than trying to explain the Lister/Listeroid issue, and I will have a 6/1 in about 60 days) He said as long as the frame is rigid he sees no reason why that would not work.  He suggested I talk to a company they use called Ebco   http://www.ebco-inc.com  about which mounts would be appropriate for my situation. 

I am sure there will be people who are skeptical of the account of a phone conversation I had, fair enough.  I will e-mail the sketch of the frame to the engineer tonight and will post the reply from him (and he better reply) 

To recap I have spoken to 2 engineers and both said mounting could be done with resiliant mounts.  Granted this is a small number and will likely be dismissed as too small of a sample, how many would be an acceptable sampling?

Perhaps this will shed additional light on this subject and maybe, just maybe put it to bed once and for all.

Naaah  I have a feeling the beat will go on.

Scott
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6/1

mobile_bob

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Re: concrete vs resilient mounting
« Reply #10 on: October 04, 2006, 07:35:14 PM »
very fascinating Scott

would be quite interesting to get an email from lister petter outlining the possible use of a rigid subframe and the use of resilient mounts...
if he was to look over your sketch and approve of it at least in principle and email you back. hmmmm

i guess that might change the hue of the debate a bit.


very interesting

bob g
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Quinnf

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Re: concrete vs resilient mounting
« Reply #11 on: October 04, 2006, 10:00:38 PM »
That assumes there is anyone still working there that knows anything about the dynamics of one-lung engines.  That was a product that was in its prime 50-70 years ago.  As the market moved toward smaller displacement, multicylinder higher RPM engines, the guys who really understood what was going on with the rock-crushers probably found no one to pass their wisdom to, save an occasional sympathetic barkeep in the pub down the street.  When contacting manufacturers about legacy products I've learned they sometimes tell you what they think you want to hear just to get you off the phone.  So as always, keep yer eyes open and don't pass up the opportunity to scrutinize advice (mine included, I suppose).

Quinn
« Last Edit: October 04, 2006, 10:20:00 PM by Quinnf »
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xyzer

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Re: concrete vs resilient mounting
« Reply #12 on: October 04, 2006, 10:36:34 PM »
So as always, keep yer eyes open.
Quinn

You got that right Quinn! I have been watching both sides of this issue for some time and even participated in some of the discussions....There are several Listeroids out there doing there little jiggle on rubber do dads and doing very well...I have one...I'm not the only one for sure...My point is I can show how it works with a balanced 6/1 and all I have asked is where are all of the broken cranks....60-70 years is a long time to break a few....Not someones theory.....Facts work well! No one has as of yet has shown us what a original CS 6/1 Lister looks like running on cement loose..! I would love to see how well they are really balanced! That would help alot in explaining to me why they recomend there mounting procedure. I wanna know!.....Fact is balancing cost money...pay more for the product!....cement was cheap.....thats my theory! The math is called the bottom line...still used today!
« Last Edit: October 04, 2006, 10:38:10 PM by xyzer »
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Procrustes

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Re: concrete vs resilient mounting
« Reply #13 on: October 04, 2006, 11:01:50 PM »
that is the fundamental difference between you and me i suppose.

you accept as fact because that is what you are told or read, i accept what as fact, only after scrutinizing what i have been told or read. 

I'll assume you didn't intend to say that I am an idiot and you are not, but you did.

we both come to the same conclusion although from different approaches

My conclusion is that it is presumptuous to question RA Lister's competence.

again i accept the solution, but do not accept as of yet the reasoning as being fact

Not sure I understand.

Basically if the answer is concrete, then i want to see the calculations or the lister work that brought them to their conclusion.

this is no different than Guy asking Guy Incog for his math to support his contention that a particular resilient mount will work.

GI asserts that abc mount will work for the intended purpose, and Guy asks to see his computations.  That is fair is it not?

so conversely

if Guy asserts that xyz mount will work, then i should be well within reason to ask to see the computations, That too is fair is it not?

If you're curious, more power to you.  If you doubt the CS design, then the burden of proof is on you.  As stated above, the CS has millions of hours of runtime and years of engineering.  You could equally well   assert that the crank diameter is wrong or the number of teeth on the idler gear or the tappet face size, and ask for proof to the contrary.

As far as finding experts that repudiate the CS manual, well sure you can find them.  With enough effort you'll find an ME who recommends doughnuts for mounting your engine.  Experts designed the Tacoma Narrows bridge, too.  If you're sold on the CS, why not listen to the engineers that designed it?

Guy_Incognito

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Re: concrete vs resilient mounting
« Reply #14 on: October 05, 2006, 03:15:57 AM »
Ok, I'll post a few things here - I was going to reply to you about these things in my resilient engine mount thread Guy_F,  but I don't want to clutter it. Lord knows its cluttered enough already.

Quote from: Guy_F
Nobody has ever asked me if I ever did or saw done any analysis of the loads on a lister, there is a pretty big clue in the four 3/4" bolts lister used, guy incognito is in between branding me a luddite playing with spreadhseets and coming up with forces of 150 kilos on the engine mounts, and slightly worried by it,

If you'd care to read my thread completely, that 150kg was for a guesstimated piston imbalance only.
Not rotating imbalances.
Or torque reaction.
Or any other force that I can't think of off the top of my head. I'm sure there's a few more. Enlighten me if you know.

Quote
y'all could have asked me because I have seen these tests done with proper strain gauges and data capture on a 6/1 driving a hydraulic pump under the full range of loads, and guy incognito is nearly an order of magnitude out, I saw amplitude ranges of in excess of 1000 kilos under certain conditions, and some of the second and third order harmonics of these loads were a bitch too..... again, those 3/4" bolts lister used make a lot of sense if you look at them with an open mind and let what you are looking at seep in and percolate.

I have asked you. I've asked for figures and data to back it up, in quite a few block vs rubber threads. and just NOW you're suddenly pointing out that you've done all the practical work that I'm trying to encapsulate in theory? You could have used that last paragraph as a powerful rebuttal to a number of arguments about the safety of concrete vs resilient mounts..... but you didn't. Why? And out of interest, where where the sensors located on that system?

Quote
The concrete block also allowed you to follow lister directions and leave the top few inches of bolt free and unfixed, so those loads are spread along a length of bolt instead of being concentrated in one point, all for fatugue see.

Good, good. So there's a bit of give between engine and concrete? I thought this thing was a rigid mount? You know, if there's give, there's a spring factor, and if theres a spring factor.... it's a resilient mount. Of sorts.

Quote
If you have an engine that is dancing, eg an engine that you can stick a feeler gauge under when it is running, then by definition there was enough force reacting on the engine to reduce its effective "weight" to zero momentarily.

See above comment. Does that mean I could calculate the spring rate of the 4 bolts and show you where the resonant frequency is? Picking a ludicrous (for resilient mounts) spring rate such as 2MN/m gives me a resonant point at a range of figures between 400-800RPM depending on damping and whether power pulses are the dominant driving force under full load. Ring any bells?

In any case, reducing it's effective weight to zero is a heckavalot of force in anyone's language. Are you sure that thing was really balanced well? Just makes me wonder about the "bung it on a two ton block, the sucker won't go anywhere then" theory as being the default for lister because they didn't care much for engine balance. 

(edit: bloody nested quotes, again.)
« Last Edit: October 05, 2006, 03:20:29 AM by Guy_Incognito »